1. Field
The invention relates to a solar roofing assembly comprising devices capable of collecting solar energy in order to provide electrical and thermal energy, such as electricity-generating photovoltaic systems and solar collectors used for hot-water production, respectively.
2. Description of the Related Art
For a number of years, for economic reasons, there has been a growing interest in the use of solar energy for partly meeting the electricity and/or hot-water consumption requirements of homes or commercial premises.
To meet electricity requirements, it is known to place photovoltaic modules on roofs, said modules comprising photovoltaic cells coupled in series to one another and generating a DC current when they are exposed to light.
In general, a photovoltaic module is formed from a photovoltaic panel incorporating the photovoltaic cells and a metal frame surrounding and supporting the panel, this frame moreover incorporating the electrical distribution cables. The photovoltaic panel is designed, at least on its front face, the one facing the external environment, with a glass substrate. To give an example, the panel includes a glass substrate therefore constituting its front face, a plastic film or a glass substrate constituting its rear face. Inserted between the front and rear face substrates are one or more polymer interlayers and a photovoltaic element, which is formed by a stack of semiconductor materials sandwiched between two metal electrodes. The semiconductor materials are, for example, based on crystalline silicon or on thin films.
For specific hot-water requirements, particularly for sanitary use and possibly for floor or wall heating, it is also known to provide roofs with solar collectors. In particular, these collectors take the form of modules, which include a transparent cover, such as a glass substrate, and an absorber. The absorber is an element through which a heat-transfer fluid flows, such as simply water to be heated. The transparent cover lets the solar radiation pass through it to the absorber, in order to heat the fluid flowing therein, and advantageously confines the infrared radiation, thus minimizing absorber cooling. Furthermore, to prevent thermal losses from the absorber, a thermal insulation is placed to the rear and around the periphery of the module.
However, depending on the sunshine or certain temperature conditions, such as winter conditions, these solar collectors are incapable of providing sufficiently hot water. It is therefore necessary to couple water production to a complementary installation for heating water by gas or electricity, which in the end results in production costs that are not always economic considering the purchase cost and installation cost of these collectors.
Moreover, other systems using the solar energy resource, such as thermal modules delivering hot air, are known. For this purpose, United States patent application US 2006/0118163 not only proposes to place photovoltaic modules on a roof but also hot-air thermal modules. These hot-air thermal modules or collectors include substrates that let through the solar energy, and a space in which air is confined so as to be heated thanks to said energy. Distribution ducts are connected to these modules for capturing hot air and in order to feed air to be heated into the confinement space.
However, although such thermal modules may be used for hot-air production, they do not meet hot-water production requirements insofar as the air/water heat exchangers would necessitate a considerable heat exchange area and would not enable the required temperatures for domestic hot water, especially for sanitary purposes, to be achieved.
It may be envisioned to combine these photovoltaic modules and hot-air and/or hot-water thermal solar collectors on roofs. However, as currently configured, they result in a substantial investment for a dwelling. In practice, homeowners choose instead to install high-performance insulation in their homes, optionally combined with one or other of the thermal energy and electrical energy supply solutions described above, but rarely combine these solutions.
In addition, these photovoltaic modules and thermal solar collectors, although able to be integrated into the roofing and attached without projecting from the roofing, do not provide an aesthetically attractive unit over the entire surface of the roof.
The object of the invention is therefore to provide a solar roofing assembly that incorporates at least one photovoltaic device and at least one thermal solar collector for hot-water production, this roofing assembly having the following advantages:                low installation costs;        delivery of a highly efficient assembly, producing, thanks to the thermal solar collector and to the exclusive configuration of the roofing, without requiring complementary independent heating systems, very hot water directly usable for sanitary purposes;        minimal thermal loss;        a guaranteed attractive appearance.        